P
US6838693B2ExpiredUtilityPatentIndex 99

Nitride semiconductor device

Assignee: NICHIA CORPPriority: Jul 7, 2000Filed: May 22, 2003Granted: Jan 4, 2005
Est. expiryJul 7, 2020(expired)· nominal 20-yr term from priority
Inventors:KOZAKI TOKUYA
H10H 20/821H10H 20/812H10H 20/825H01S 5/18369H01S 5/305H01S 5/34333H01S 5/2009H01S 5/22H01S 5/3054H01S 5/18308H01S 5/3086H01S 2304/12H01S 5/343B82Y 20/00H01S 5/3415H01S 5/3407
99
PatentIndex Score
75
Cited by
39
References
48
Claims

Abstract

A nitride semiconductor device has an active layer of a quantum well structure sandwiched between p-type nitride semiconductor layer 11 and n-type nitride semiconductor layer 13. The active layer has, a barrier layer formed by a first barrier and a second barrier layer which sandwich the well layer in between. The first barrier layer being arranged on the p-side of the well layer and the second barrier layer being arranged on the n-side of the well layer.

Claims

exact text as granted — not AI-modified
1. A nitride semiconductor device having a structure wherein an active layer of a quantum well structure, which has a well layer made of a nitrid semiconductor and a barrier layer made of a nitride semiconductor, is sandwiched between a p-type nitride semiconductor layer and an n-type nitride semiconductor layer;
 wherein said active layer has, as said barrier layer, a first barrier leyer and a second barrier layer sandwiching said well layer in between; said first barrier layer being arranged on p-side of said well layer and said second barrier layer being arranged on n-side of said well layer; the thickness of said first layer being greater than the thickness of said second barrier layer.  
 
     
     
       2. The nitride semiconductor device according to  claim 1 , wherein said first barrier layer is arranged in the outermost position within said active layer. 
     
     
       3. The nitride semiconductor device according to  claim 1 , wherein said second barrier layer includes an n-type impurity. 
     
     
       4. The nitride semiconductor device according to  claim 3 , the concentration of an n-type impurity in said well layer is not greater than that of said barrier layers including the n-type impurity. 
     
     
       5. The nitride semiconductor device according to  claim 1 , wherein said first barrier layer does not substantially include an n-type impurity. 
     
     
       6. The nitride semiconductor device according to  claim 1 , wherein the concentration of a n-type impurity in said first barrier layer is not more than 5×10 16  cm −3 . 
     
     
       7. The nitride semiconductor device according to  claim 1 , wherein said first barrier layer includes a p-type impurity. 
     
     
       8. The nitride semiconductor device according to  claim 1 , wherein at least one of said well layers has the thickness of not less than 20 Å and ot more than 200 Å. 
     
     
       9. The nitride semiconductor device according to  claim 1 , wherein said active layer has 2 or more well layers and a third barrier layer intervened between the well layers; the film thickness of said third barrier layer being smaller than the film thickness of said first barrier layer and said second barrier layer. 
     
     
       10. The nitride semiconductor device according to  claim 1 , wherein said first barrier layer or said second barrier layer comprises two layers that are different in a composition or an impurity concentration with each other. 
     
     
       11. The nitride semiconductor device according to  claim 10 , wherein one of said two layers is made of nitride semiconductor including Al. 
     
     
       12. The nitride semiconductor device according to  claim 1 , wherein said p-type nitride semiconductor layer has a first p-type nitride semiconductor layer adjoining said active layer, and said first p-type nitride semiconductor layer is made of a nitride semiconductor that includes Al. 
     
     
       13. The nitride semiconductor device according to  claim 12 , wherein said first barrier layer is arranged to contact with said first p-type nitride semiconductor layer. 
     
     
       14. The nitride semiconductor device according to  claim 13 , wherein said first p-type nitride semiconductor layer is doped with a p-type impurity in higher concentration than said first barrier layer. 
     
     
       15. The nitride semiconductor device according to  claim 1 , wherein the number of well layers in said active layer is from 1 to 3. 
     
     
       16. The nitride semiconductor device according to  claim 1 , wherein said second barrier layer is sandwiched between two well layers; and the thickness ratio R t  of said second barrier layer to said well layer is in the range of 0.5≦R t ≦3. 
     
     
       17. The nitride semiconductor device according to  claim 1 , wherein said p-type nitride semiconductor layer includes a p-side optical guide layer and a p-side clad layer formed sequentially on said active layer; and said p-type nitride semiconductor layer is partially cut away to the depth that a part of said p-side optical guide layer is removed to form a ridge stripe structure. 
     
     
       18. A nitride semiconductor device having a structure wherein an active layer of a quantum well structure, which has a well layer made of a nitride semiconductor and a barrier layer made of a nitride semiconductor, is sandwiched between a p-type nitride semiconductor layer and an n-type nitride semiconductor layer;
 wherein said active layer has L (L≧2) barrier layers so that the barrier layer arranged in a position nearest to said n-type nitride semiconductor layer is denoted as barrier layer B 1  and the i-th barrier layer (i=I, 2, 3, . . . L) counted from the barrier layer B 1  toward said p-type nitride semiconductor layer is denoted as barrier laye B i ; the thickness of the barrier layer B L  being greater than the thickness of the barrier layer B i  (i≠L).  
 
     
     
       19. The nitride semiconductor device according to  claim 18 , wherein said barrier layer B L  is arranged in the outermost position within said active layer. 
     
     
       20. The nitride semiconductor device according to  claim 18 , wherein the barrier layers Bi from i=1 to i=n(I<n<L) include an n-type impurity. 
     
     
       21. The nitride semiconductor device according to  claim 20 , wherein the concentration of an n-type impurity in said well layer is not greater than that of said barrier layer including the n-type impurity. 
     
     
       22. The nitride semiconductor device according to  claim 18 , wherein said barrier layer B L  does not substantially include an n-type impurity. 
     
     
       23. The nitride semiconductor device according to  claim 18 , wherein the concentration of a n-type impurity in said barrier layer B L  is not more than 5×10 16  cm −3 . 
     
     
       24. The nitride semiconductor device according to  claim 18 , wherein said barrier layer B L  includes a p-type impurity. 
     
     
       25. The nitride semiconductor device according to  claim 18 , wherein at least one of said well layers has the thickness of not less than 20 Å and not more than 200 Å. 
     
     
       26. The nitride semiconductor device according to  claim 18 , wherein the film thickness of said barrier layer Bi(I<i<L) is smaller than the film thickness of said barrier Layer B 1 . 
     
     
       27. The nitride semiconductor device according to  claim 18 , wherein at least one of said barrier layers Bi (1≦i≦L) comprises two layers that are different in a composition or an impurity concentration with each other. 
     
     
       28. The nitride semiconductor device according to  claim 18 , wherein said p-type nitride semiconductor layer has a first p-type nitride semiconductor layer adjoining said active layer, and said first p-type nitride semiconductor layer is made of a nitride semiconductor that includes Al. 
     
     
       29. The nitride semiconductor device according to  claim 28 , wherein said barrier layer B L  is arranged to contact with said first p-type nitride a semiconductor layer. 
     
     
       30. The nitride semiconductor device according to  claim 29 , wherein said first p-type nitride semiconductor layer is doped with a p-type impurity in higher concentration than said barrier layer B L . 
     
     
       31. The nitride semiconductor device according to  claim 18 , wherein the number of well layers in said active layer is from 1 to 3. 
     
     
       32. The nitride semiconductor device according to  claim 18 , wherein said barrier layer B n  (1≦n<L) is sandwiched between two well layers; an the thickness ratio R t  of said barrier layer B n  to said well layer is in the range of 0.5≦R t ≦3. 
     
     
       33. The nitride semiconductor device according to  claim 18 , wherein said p-type nitride semiconductor layer includes a p-side optical guide layer and a p-side clad layer formed sequentially on said active layer; and said p-type nitride semiconductor layer is partially cut away to the depth that a part of said p-side optical guide layer is removed to form a ridge stripe structure. 
     
     
       34. A nitride semiconductor device having a structure wherein an active layer of a quantum well structure, which has a well layer made of a nitride semiconductor and a barrier layer made of a nitride semiconductor, is sandwiched between a p-type nitride semiconductor layer and an n-type nitride semiconductor layer,
 wherein said active layer has a first barrier layer arranged in a outermost position close to said p-type nitride semiconductor layer and a second barrier layer arranged in a outermost position close to said n-type nitride semiconductor layer; the film thickness of said first barrier layer being greater than said second barrier layer.  
 
     
     
       35. The nitride semiconductor device according to  claim 34 , wherein said second barrier layer includes an n-type impurity. 
     
     
       36. The nitride semiconductor device according to  claim 35 , wherein the concentration of an n-type impurity in said well layer is not greater than that of said barrier layers including the n-type impurity. 
     
     
       37. The nitride semiconductor device according to  claim 34 , wherein said first barrier layer does not substantially include an n-type impurity. 
     
     
       38. The nitride semiconductor device according to  claim 34 , wherein the concentration of a n-type impurity in said first barrier layer is not more than 5×10 16  cm −3 . 
     
     
       39. The nitride semiconductor device according to  claim 34 , wherein said first barrier layer includes a p-type impurity. 
     
     
       40. The nitride semiconductor device according to  claim 34 , wherein at least one of said well layers has the thickness of not less than 20 Å and not more than 200 Å. 
     
     
       41. The nitride semiconductor device according to  claim 34 , wherein said active layer has 2 or more well layers and a third barrier layer intervened between the well layers; the film thickness of said third barrier layer being smaller than the film thickness of said first barrier layer and said second barrier layer. 
     
     
       42. The nitride semiconductor device according to  claim 34 , wherein said first barrier layer or said second barrier layer comprises two layers that are different in a composition or an impurity concentration with each other. 
     
     
       43. The nitride semiconductor device according to  claim 34 , wherein said p-type nitride semiconductor layer has a first p-type nitride semiconductor layer adjoining said active layer, and said first p-type nitride semiconductor layer is made of a nitride semiconductor that includes Al. 
     
     
       44. The nitride semiconductor device according to  claim 43 , wherein said first barrier layer is arranged to contact with said first p-type nitride semiconductor layer. 
     
     
       45. The nitride semiconductor device according to  claim 44 , wherein said first p-type nitride semiconductor layer is doped with a p-type impurity in higher concentration than said first barrier layer. 
     
     
       46. The nitride semiconductor device according to  claim 34 , wherein the number of well layers in said active layer is from 1 to 3. 
     
     
       47. The nitride semiconductor device according to  claim 34 , wherein said second barrier layer is sandwiched between two well layers; and the thickness ratio R˜ of said second barrier layer to said well layer is in the range of 0.5≦R t ≦3. 
     
     
       48. The nitride semiconductor device according to  claim 34 , wherein said p-type nitride semiconductor layer includes a p-side optical guide layer and a p-side clad layer formed sequentially on said active layer; and said p-type nitride semiconductor layer is partially cut away to the depth that a part of said p-side optical guide layer is removed to form a ridge stripe structure.

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